Here are some of the latest health and medical news developments, compiled by the editors of HealthDay:

Alzheimer's Prevention Study Gets $33 Million Grant

The U.S. government said Wednesday that it has given a $33.2 million grant to a study that will test if a drug can prevent Alzheimer's in people at greatest risk for developing the most common form of the disease.

The grant was awarded to researchers at the Banner Alzheimer's Institute in Phoenix. The clinical trial will focus on the late-onset form of the disease, which affects the vast majority of the 5 million Americans estimated to have Alzheimer's, The New York Times reported.

The study will include people ages 60 to 75 who do not have any symptoms of the disease, but do have two copies of a gene known to greatly increase the risk of developing it.

This is the largest federal grant ever awarded to test a drug specifically designed to prevent Alzheimer's in people without symptoms, said Laurie Ryan, program director for Alzheimer's disease clinical trials at the National Institute on Aging, part of the National Institutes of Health, The Times reported.

The government on Wednesday announced a total of $45 million in grants for Alzheimer's research.

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Percentage of Americans Without Health Insurance Falls for Second Year in a Row

The percentage of Americans without health insurance declined for a second year in a row in 2012, despite little change in household income and the poverty rate, the Census Bureau reported.

According to the findings, 15.4 percent of people were uninsured last year, compared with 15.7 percent in 2011. There were 48 million uninsured people in 2012 compared to 48.6 million in 2011, The New York Times reported.

The proportion of adults aged 19 to 25 without insurance fell to 27.2 percent last year. While not significantly lower than in 2011, it was down from 29.8 percent in 2010.

The proportion of children younger than 19 without insurance declined to 9.2 percent in 2012, from 9.7 percent in 2011, which may be the result of the provision in the 2010 health care law that allows young adults to stay on their parents' insurance policies until age 26, The Times reported.

Much of the rise in health insurance coverage in 2012 was due to government programs, according to David Johnson, the chief of social and economic statistics at the bureau. He noted that Medicare provided coverage for 15.7 percent of the population last year, compared with 15.2 percent in 2011.

Among the other findings:

The proportion of Hispanics without health coverage last year was 29.1 percent, 1 percent lower than in 2011. But the percentage of Hispanics without health insurance in 2012 was still much higher than that of blacks (19 percent), Asian-Americans (15.1 percent) and whites (11.1 percent).

The percentage of foreign-born people without health insurance in 2012 was 32 percent, compared with 13 percent for native-born Americans.

Two of the nation's four major regions, the South and the West, had 61 percent of the U.S. population in 2012 but accounted for 71 percent of all of the uninsured people.

People with lower incomes were much more likely to be uninsured than those with higher incomes. The uninsured rate was 24.9 percent among people in households with annual incomes of less than $25,000, compared with 7.9 percent for those in households with incomes of $75,000 or more.

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Michelle Obama Hosting Summit on Food Marketing to Kids

First Lady Michelle Obama is hosting the first White House summit on food marketing to children.

The goal of Wednesday's meeting is to get involved parties talking about how to promote healthier food choices for children, the Associated Press reported.

Invitations were sent to representatives from the food and media industries, advocates, parents, researchers, and representatives of government agencies, according to the White House. It did not release a list of names and organizations.

The First Lady will open the summit with public remarks, but the rest of the meeting will be closed to the media, the AP reported.

Research shows that food marketing is a leading cause of obesity among children, according to consumer advocates. A 2006 Institute of Medicine report said that food and beverage marketing to children "represents, at best, a missed opportunity, and, at worst, a direct threat to the health of the next generation."